The measurement of fluid flow through a centrifugal pump with convenient read-out of repeatable accuracy has generally been a difficult process and typically requires the attachment of sensors and instrumentation downstream of the pump. At the same time, there is a demand for a simple, effective and reliable means for measuring fluid flow at the pump itself. A typical centrifugal pump of the prior art comprises an impeller, rotatably mounted in a stationary casing with the rotating impeller imparting pressure and kinetic energy to the fluid being pumped, and the stationary casing guiding the fluid to and from the impeller. In a typical centrifugal pump casing, which generally includes concentric, diffusor and volute type centrifugal casings, the rotation of the impeller imparts kinetic energy to the fluid and causes fluid flow, in a generally circular direction about the perimeter of the impeller, through the casing surrounding the impeller. At some point in the casing the fluid flows from the perimeter of the impeller, passes a cut-water or the like through a area of the pump generally known as the discharge inlet area and through the discharge nozzle to the pump discharge.
In the operation of the pump, the fluid flow can be affected by the design of the impeller, the design and size of the casing, the speed at which the impeller rotates, the design and size of the pump inlet and outlet, quality of finish of the components, presence of a casing volute and the like. The incorporation of flow measurement devices within the pump are typically seen as creating added obstruction to fluid flow and further flow variations.
Thus the convenience of a relatively easy means for the measurement of fluid flow integral with the centrifugal pump has not been generally available in the industry and is long overdue.
The principal object of this invention is to provide a centrifugal pump adapted for measuring fluid flow.
Another object of this invention is to provide a method for the measurement of fluid flow through a centrifugal pump which is convenient and relatively non obstructive to fluid flow. These and other objects of the invention will become apparent from the following.